Machine for straightening elongated objects

ABSTRACT

Opposed straightening rolls are mounted within a U-shaped frame, their axes being parallel and at an angle relative to the longitudinal axis of the object to be straightened. One of the rolls is segmented into three separate rollers with the axes of the outer rollers eccentric to the axis of the center roller and adjustable along an arc. The points of contact between the rollers and workpiece are arranged to define a plane containing the longitudinal axis of the workpiece.

St tent r191 [11] 3324,31

Hartkopf Dec. 9, 1975 MACE FOR STRAIGHTENING ELONGATED OBJECTS Inventor:Heinz Hartkopf, Solingen, Germany Th. Kieserling & Albrecht, Solingen,Germany Filed: Aug. 28, 1974 Appl. No.: 501,149

Assignee:

Foreign Application Priority Data Sept. 5, 1973 Germany 2344613 US. Cl72/98; 72/99 Int. Cl. B21D 3/04 Field of Search 140/147; 72/98, 99, 100

References Cited UNITED STATES PATENTS 7/1973 Hartkopf 72/99 PrimaryExaminer-Lowell A. Larson Attorney, Agent, or Firm-Edward E. SachsABSTRACT Opposed straightening rolls are mounted within a U- shapedframe, their axes being parallel and at an angle relative to thelongitudinal axis of the object to be straightened. One of the rolls issegmented into three separate rollers with the axes of the outer rollerseccentric to the axis of the center roller and adjustable along an arc.The points of contact between the rollers and workpiece are arranged todefine a plane containing the longitudinal axis of the workpiece.

8 Claims, 3 Drawing Figures Patent De. 9 1975 Sheet 1 of 3,924,431

U.S., Patent Dec. 9 1975 Sheet 2 of2 3,924,431

MACHINE FOR STRAIGHTENING ELONGATED OBJECTS This invention relates tostraightening devices, and more particularly to equipment forstraightening elongated workpieces such as rods or pipes.

Straightening equipment of the type contemplated, generally employsopposed straightening rolls, rotating about longitudinal axes which areat an angle to the longitudinal axis of the workpiece. The rolls on oneside may be divided into three rollers, each mounted upon parallel axes,with the outer rollers being eccentn'cally mounted and adjustable alongan arcuate path, relative to the central roller.

Experience indicates that the straight-edges used with such equipmentmust be frequently replaced due to excessive wear. Attempts to replacethem with supporting rollers have failed to produce satisfactoryresults. On two-roll machines, such as disclosed for example in GermanOffenlegungsschrift DT-OS No. 1,910,879, it was impossible to provide asatisfactory solution to the rapid wear of the straight-edges. Replac'ing the straight-edges with supporting rollers created new problems,particularly when working on highstrength small diameter workpieces.Also, thin workpieces are not properly guided and tend to wander fromthe proper path through the equipment.

Some progress towards straightening without a straight-edge, although itis not a complete solution, is suggested in German Auslegeschrift DT-ASNo. 2,113,713. In this disclosure, particularly large supporting rollersprovide a long narrow guidance cap for the workpiece, between two bottomouter rollers and the top roll. Here again, however, considerabletransverse forces are produced by the one-piece hyperbolic roll that isused. These forces must be absorbed by the supporting rollers.

The present invention uses a unique arrangement of a segmented rollhaving three rollers to reduce or eliminate the forces which createexcess wear. This arrangement positions the points or lines of contactbetween the three rollers and the workpiece such that they liesubstantially within a plane which also contains the longitudinal axisof the workpiece. To efi'ect this, the two outer rollers are displacedin relation to the central roller, towards the workpiece, so that thecenters of the three rollers and the longitudinal axis of the workpiecedefine a plane. Since the rollers and workpiece are of circular crosssection, if the line joining the centers of the three rollers lies inthe same plane with the longitudinal axis of the workpiece, the pointsor lines of contact will lie in the same plane.

The two outer rollers, with their points of contact with the workpiece,are the corners of the triangle of bending and, according to theinvention, they act as straightening rolls. The forces applied by theouter rollers to the work-piece are, at least theoretically, purebending forces and have no detrimental components such as transverseforces. The forces applied by the rollers to the workpiece all lie inthe plane which includes the centers of the rollers and the workpiece,and they are all theoretically absorbed by the second roll, the centerof which lies in the same plane. Straightening with a divided hyperbolicroll according to the invention is basically a problem of planes, andany straightedge serves merely as a guide subjected to a minimum ofwear. Because of the reduced pressure of the work- 2 piece upon such astraight-edge, synthetic materials may be used along the working edges.In fact, the entire straight-edge may be made of synthetic material.

It is an object of the invention to provide an improved straighteningdevice.

Another object of the invention is to provide a straightening devicewhich creates a minimum of wear upon the guiding straight-edges.

Another object of the invention is to provide a straightening devicehaving improved spring characteristics and ease of roll adjustment.

In accordance with a particular embodiment of the invention,straightening equipment for elongated worpieces is provided with opposedstraightening rolls having their axes positioned at an angle to thelongitudinal axes of the workpiece. One of the straightening rolls issegmented into three separate rollers mounted on parallel axes, the twoouter rollers being mounted eccentrically in relation to the centralroller and being adjustable in relation thereto, along an arc. Thepoints of contact between the rollers and the workpiece are arranged tolie in the same plane as the longitudinal axes of the workpiece.

For a better understanding of the present invention, together with otherand further objects thereof, reference is had to the followingdescription taken in connection with the accompanying drawings, and itsscope will be pointed out in the appended claims.

In the drawings:

FIG. 1 is a front elevation of a straightening unit according to anillustrative embodiment of the invention;

FIG. 2 is a horizontal section through the unit shown in FIG. 1, at thelevel of the straightening gap; and

FIG. is a plan view of FIG. 2.

FIG. 1 illustrates a straightening machine having a main frame 1 with atable 2 and two side members 3, 4 extending upwardly therefrom to definea U-shaped gap. Apertures 11 and 12 are provided in the diagonallyopposite lateral faces of the side members 3, 4 so that the workpiecemay pass diagonally through the straightening machine. A segmented topstraightening roll 5 is mounted in the side members 3, 4 within the gap,and is divided into three parts, or rollers, 5a, 5b, 50. A bottomstraightening roll 6 is mounted in journals 7 directly below top roll 5.The journals 7 run in a roll holder 8 that is mounted to the table 3 ina vertically adjustable manner. A threaded shaft, hydraulic system, orother means may be provided for this adjustability. Straight-edges areprovided approximately along the path of the workpiece between the topand bottom rolls, for the purpose of guiding the workpiece. For reasonsof clarity, only a rear straight-edge 9, with wearing edges 9a, 9b, isshown. The straight-edge 9 has a recess 10 for bottom roll 6.

Outer rollers 5a, 5c are eccentrically mounted relative to centerrol1er5b and to adjust for sag or bowing of the workpiece, adjustingmechanisms 13, 14 are provided. These mechanisms permit the raising orlowering of the outer rollers along a slightly curved path.

The position of a workpiece 15 relative to the rollers 5a, 5b, 5c isseen in FIGS. 2 and 3. Center lines 16, 17 show that the two outerrollers 5a, 50 are mounted eccentrically of the center roller 5b, theouter rollers being displaced towards the workpiece 15 which advancesdiagonally through the straightening machine. This establishes points ofcontact 20, 21, 22 directly below .the center lines of the "relevantrollers, i.e. contact point 20 lie's vertically below center line 16,

contact point 21 lies vertically below center line 18, and contact point22 lies vertically below center line 17. The plan view of FIG. 3 showsclearly that contact points 20, 21, 22 lie vertically under the rollercenters and in the same plane as the dotted center line 23 of work-piece15. Center line 23 also represents the straightening plane.

Depending upon the particular job,.all three rollers may be driven by adriving wheel 24; the central roller being driven directly and the twoouter rollers by planetary drives. Typical design details for drivingthe outer rollers appear in aforecited German Auslegeschrift DT-AS No.2,113,713. Bottom roll 6 may be driven by a motor via a cardan shaft andtransmission. Roll holder 8 may have a bearing adapted to rotate about avertical axis passing through the center of bottom roll 6 and/orhydraulic support means for the said holder.

If outer rollers 5a, 5c are lowered to a sufficiently great extent, theworkpiece can be prevented from coming into contact with center roller5b. This enables the machine to execute free bends. Embossing orpolishing can be carried out by raising the outer rollers 5a, 5c.

The hyperbolic form of the straightening roll is ad vantageous; however,as noted above the main defect of this hyperbolic form is the productionof transverse forces. In accordance with the invention, the outerrollers 5a, 5c of the segmented roll 5 are provided with convexsurfaces, while the inner roller 5b is provided with a concave surface.Experience with this arrangement indicates that the straighteningeffects are comparable to those achieved with conventional 2-rollmachines.

It will be seen that with the structure of this invention, one adjustsfor the sag in the workpiece by merely rotating the axes of outerrollers 5a and 5c in order to modify their eccentricity relative to thecentral roller 5b. There is no change in the position of the centralroller 5b nor is there any rotation of the central roller about avertical axis.

It will be appreciated that rotation of the outer rollers 5a and 50along an axis about the longitudinal axis of center roller 5btheoretically makes it impossible to fulfill the requirement that thepoints of contact lie in a plane with the longitudinal axis of theworkpiece. In practice, however, the deviation from the idealgeometrical form is minimal and not significant. In effect, there is along lever ann relationship involved so that the minimum angulardisplacements in the vicinity of dead center do not detrimentally effectthe substantially planar relationship between the various points ofcontact and the workpiece axis.

Although the invention may be practiced in embodiments wherein the lowerroll is segmented, rather than the upper roll, it has been foundadvantageous to employ the basic structure illustrated in the embodimentof FIG. 1. With this structure, it is not necessary to rotate thecentral roller 5b about a vertical axis and accordingly it can bemounted directly to rigid vertical members 3, 4 of the machine 1. Thiseliminates the need for a cross-bar joining the side members and/ormeans for radially adjusting the top roll 5.

With the axis of the center roller 5b fixedly established, thestraightening gap is controlled by vertical positioning of the bottomroll 6 only. Of course, the straightening gap is adapted to the diameterof the workpiece being handled and variations in the straightening gapcause a displacement of the longitudinal axis of the workpiece. Forexample, when changing from a larger to a smaller diameter workpiece,the center line of the workpiece is displaced in an upward direction.This requires commensurate displacement of the input and outputchannels. However, as the diameter decreases, the sag required forstraightening increases and the ends of the workpieces projecting beyondthe rolls, drop. This leaves only the difference in displacement andsharply reduces the necessary adjustability of the input and outputchannels as a whole.

Those skilled in the art are familiar with the pearshaped deformation ofthe ends of workpieces, created as they enter or leave straighteningmachines. It is believed that the spring in the frame of the machine isbasically responsible for this deformation. By rigidly mounting the axisof the top roll, with no provision for angular adjustment, one is ableto achieve a particularly stiff machine, i.e. one having a sharpcharacteristic spring curve for the frame of the machine. Indeed, in theabsence of a cross-bar across the vertical members 3-4, these membersmust have a relatively large cross-section; however, this increase incross-section is easily offset by the elimination of the cross-bar withits attendant weight. Still further, increased mass in the verticalmembers 3, 4 has the additional effect of reducing their elasticity andimproving the stiffness characteristic of the entire unit.

While there has been described what is at present considered to be apreferred embodiment of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the invention, and it is aimed,therefore, in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

I claim:

1. A straightening machine for elongated workpieces comprising: opposedstraightening rolls having axes positioned at an angle to thelongitudinal axis of the workpiece, one of said straightening rollsincluding three rollers mounted on parallel axes, the two outer rollersbeing mounted eccentrically in relation to the center roller and beingadjustable in relation thereto along an arc, the points of contactbetween said rollers and said workpiece being in a plane with thelongitudinal axis of the workpiece.

2. A straightening machine according to claim 1, wherein said two outerrollers have convexly arched peripheries and said center roller has aconversely arched periphery.

3. A straightening machine as defined in claim 1, wherein said opposedstraightening rolls are positioned vertically, one above the other; saidthree rollers comprising the upper one of said rolls.

4. A straightening machine as defined in claim 3, wherein said rolls arepositioned between two vertical support members, the rollers of saidupper roll being journalled directly in said support members.

5. A straightening machine as defined in claim 4, wherein said verticalsupport members are joined only at the bottom.

6. A straightening machine as defined in claim 4, wherein said two outerrollers have convexly arched peripheries and said center roller has aconversely arched periphery.

7. A straightening machine as defined in claim 3, including means forvertically adjusting the position of the lower one of said rolls.

8. A straightening machine as defined in claim 1, inroller roll andhaving a convexly arched periphery.

eluding a roll disposed generally opposed to said three

1. A straightening machine for elongated workpieces comprising: opposedstraightening rolls having axes positioned at an angle to thelongitudinal axis of the workpiece, one of said straightening rollsincluding three rollers mounted on parallel axes, the two outer rollersbeing mounted eccentrically in relation to the center roller and beingadjustable in relation thereto along an arc, the points of contactbetween said rollers and said workpiece being in a plane with thelongitudinal axis of the workpiece.
 2. A straightening machine accordingto claim 1, wherein said two outer rollers have convexly archedperipheries and said center roller has a conversely arched periphery. 3.A straightening machine as defined in claim 1, wherein said opposedstraightening rolls are positioned vertically, one above the other; saidthree rollers comprising the upper one of said rolls.
 4. A straighteningmachine as defined in claim 3, wherein said rolls are positioned betweentwo vertical support members, the rollers of said upper roll beingjournalled directly in said support members.
 5. A straightening machineas defined in claim 4, wherein said vertical support members are joinedonly at the bottom.
 6. A straightening machine as defined in claim 4,wherein said two outer rollers have convexly arched peripheries and saidcenter roller has a conversely arched periphery.
 7. A straighteningmachine as defined in claim 3, including means for vertically adjustingthe position of the lower one of said rolls.
 8. A straightening machineas defined in claim 1, including a roll disposed generally opposed tosaid three roller roll and having a convexly arched periphery.